There are many motivations to computer development, depending largely on targeted customer groups. For example, a certified public accountant needs to run applications having to do with accounting, taxes, financial planning, and the like, while a fiction writer may wish only to use a computer as a word processor. The kind of system one of these people might choose to own may be vastly different from the type the other would purchase. Manufacturers plan their research and development to produce products that appeal to their targeted customer bases.
Even with the considerable differences in needs between different consumer groups, there are still many commonly desirable traits in computer development. For example, regardless of the ultimate functionality of a particular sort of computer, a low cost to manufacture is a desirable characteristic. Another desirable characteristic is portability. There are advantages to being able to easily move one's computing tool from place to place, and even greater advantages to having a portable computer small enough to carry in a pocket or purse.
Even though portability and small size is generally desirable, power and functionality are always desirable as well, and these characteristics are competitive. Conventionally and historically one pays a penalty for small size and portability.
One of the penalties typically paid is functionality as related to battery life. That is, if one uses a powerful and fast CPU in a portable computer, the size of the battery must be quite large, and life between charges will be relatively short. For example, it can be shown in general that 100 grams of battery weight, fully charged, will power about 5×108 instructions. It is to be understood that this is a general figure, and may vary somewhat for different CPUs, types of batteries, and the like.
Given the figure above relating battery weight to a number of instructions for illustrative purposes, if a portable computer is to be provided with ability to execute relatively high-overhead applications, such a HTML files in Internet applications, the CPU for the portable computer will have to operate at 1 to 2 MIPS (million instructions per second). Assuming 1 MIPS, a battery weight of 100 g. will discharge in about 8 minutes. A five hundred gram (a little over one pound) battery will provide a life between charges of about 41 minutes.
It is seen, then, that as applications and desired functions for personal computers become more sophisticated, it becomes ever more difficult to provide theses applications and functions for small, personal, battery-powered computers.
There are some ways that battery life may be extended or optimized. For example, power-management techniques may extend battery life by 1.5, use of low-power integrated circuit technology can add another 1.5, sophisticated electrical storage technology another 1.5, and solar recharge perhaps another 1.2. The net multiplier, using every means of help is about 5, so a 500 g battery will then power such a computer for about three hours. Five hours is still a relatively short battery lifetime, so sophisticated operations for small, portable computers, such as World Wide Web (WWW) browsing on the Internet, are not, until the time of the present invention, very practical.
Further to the above discussion, as the global network of connected databases known as the World Wide Web continues to grow, social and political concerns grow as well. Many are concerned that the expense and complexity of end-use computers suitable for Web browsing is a formidable barrier to increased information access by disadvantaged millions, for which Web access may be seen as a tool for empowerment and social and political advancement.
What is clearly needed is apparatus and methods whereby sophisticated operations like Web browsing and the like may be accomplished with small, battery-powered portable computers, such as hand-held computers, while also accomplishing a life-between-charges of a week or more, without requiring especially heavy batteries.